Production of solvents from coal tar



July 28, 1942- J. HARVEY, JR 2,291,323

4 PRGDUCTION OF SOLVENTS FROM COAL TAR Filed July 13, 1940 /Wf/mr//YCHA/1455 (CA mL yar: coa/ur @MPM/y0) Patented July 28, 1942 PRODUCTIONOE' S'IOAIENTS FROM COAL J acquelin E. Harvey, Jr., Atlanta, Ga.,assignor of one-half to Southern Wood Preserving Company, East Point,Ga., a corporation of Georgia Application July 13, 1940, Serial No.345,438 2 Claims. (Cl. 196-53) The present invention relates to theproduction of valuable liquids from tars and fractions thereof, crudeand/ or rened.

An object of the present invention is the subjection of tars andfractions thereof, crude and/or rened, to the action of hydrogen instepwise manner, whereby to provide solvents of increased solvency andboiling range.

A further object of the present invention is the production of solvents,the characteristics of which are, among other things, dependent uponhydrogen supply.

Other objects of the present invention will be apparent from thefollowing disclosures.

Suitable starting materials of the present invention include tars andfractions thereof derived from coal and petroleum, as for instancecoke-oven tar, gas house tar, water gas tar and tars of aromatic contentderived from petroleum or fractions thereof; tars produced by crackinghydrocarbons; tars resulting from the action of hydrogen orhydrocarbons; tars resulting from catalytic action n hydrocarbons,including polymerization; high boiling aromatic extracts of carbonaceoussubstances; high boiling hydrocarbons of olenic and naphthenic content;tars and fractions thereof of aromatic content.

Especially attractive as starting material is high temperature coke-oventar which is available in large quantities at low price.

The present invention may be viewed broadly as providing a process forthe production of solvents by subjecting the starting material, instep-wise manner, to the controlled action of hydrogen whereby toproduce solvents of increased boiling range and enhanced solvency.

The invention will be understood from the following description ofillustrative steps comprising various methods of securing the objects ofthe invention, when read in connection with the accompanying drawingwherein thegure is a diagrammatic sketch of an apparatus for carryingout a form of the process of the invention and wherein the nature of thestep carried out in each chamber and the contents thereof are indicatedby legend.

Erample 1.-A coal tar boiling substantially 3% at 2`10 C. waspassedthrough ahigh pressure reaction chamber at 400 C. and 200 atmospherespressure; catalyst, molybdenum sulfide; time of contact, 1 hour and gasflow sufcient to provide a beneciated tar having a, lowered solvency,boiling range, specific gravity and viscosity. The thus beneciated tarwas stripped to 315 C. and the distillate therefrom boiling:

The stripped material whose end point was substantially 315 C. waspassed through a, high pressure reaction vessel at 475 C. and a pressureof 250 atmospheres with ow of hydrogen so controlled as to provide asolvent, as compared to its intermediate parent material, havingincreased boiling range, and solvency.

Example 2.-A residue from coal tar boiling substantially 3% at 380 C.,Conradson carbon 14.5 and specic gravity 1.1208 was passed through ahigh pressure reaction chamber at 410 C. and 300 atmospheres pressure;time of contact 1 hour; catalyst, cobalt sulfide and gas flow suflicientto provide a beneficiated tar fraction having a specific gravity of1.0625, a Conradson carbon of 4.89 and lower solvency than the startingproduct. The thus beneciated tar fraction was stripped to 350 C., thedistillate therefrom boiling:

Per cent I. B. P.210 C 4. 6 210-235 C 0. 4 23E-270 C 4. 0 270315 C- 34.0315-350 C 57.0

The stripped material whose end point was substantially 350 C. waspassed through a high pressure reactor at 465 C. and 300 atmospherespressure, while contacting a molybdenum-tin sulfide catalyst; ow ofhydrogen so controlled as to induce a solvent having, as compared to theintermediate starting material, an increased boiling range and solvency.

The solvents so produced maybe fractionated to provide solvents andplasticizers of any boiling range, as for instance:

. C. Benzol 78-120 Toluol -150 Hi-flash naphtha -200 Heavy naphtha150-290 Plasticizers -360 yfrom the controlled action of hydrogen that,

among other things, increases boiling range.

Looked at in. one manner, the present process provides a method fortreating aromatic tars, or

fractions thereof, with hydrogen in step-Wise manner rwhereby to producesolvents,said solvents being characterized by increased solvency, andboiling range when compared to intermediate parent material, asheretofore disclosed. The said step-wise action f hydrogen beingcharacterized by first providing hydrogen in flow that depolymerizesring multiplicities thereby inducing lowered specific gravity, boilingrange and solvency and second, by providing hydrogen in iiow thatincreases boiling range and solvency.

The aforenamed step-wise actionofhydrogen` thus provides a method forsecuring solvents of increased solvency and boiling range from heavy orhigh boiling hydrocarbons of aromatic content, said high boilerscharacterized by the presence of'ring multiplicities of great thermalsusceptibility.

The starting materials of high carbon content, as for instance hightemperature coke-oven tar or fractions thereof, are characterized by, intheir raw state, such a percentage of high molecular complexes orpolymerized products that the solvents of the present invention, that isto say, solvents of increased boiling range'and solvency, are notpossible of manufacture therefromv directly, but the starting materialmust first be subjected to the controls of the present process wherein,hydrogen flow, among other things, depolymerizes said molecularcomplexes.

The depolymerized or partially depolymerized tar or fraction of tar, isthen stripped of a percentage of its low boiling ends whereby to providethe intermediate parent material of the solvents of the present process,said intermediate material having increased boiling range and loweredsolvency. The residue incidental to said stripping may, because of its.depolymerized or partially depolymerized condition serve as recyclematerial, with or without the addition of other Vstarting material tothe end that conversion of the starting material may approach volume forvolume of said starting material into solvents of the present invention.

In the conversion of the starting material, partially or approachingunity, into the solvents of the present process, temperatures of as lowas 300 C. are usable; pressures as low as 50 atmospheres may be used.However, temperatures and pressures of an increased range provide bettercommercial practice of the present invention. The time element isdesirably that period which aords commercial recoveries of the productsof. and incidental to, the present invention.

Concerning gas flow, flows of hydrogen or hy-v drogen containing gas areusually held in excess of 2.000 cubic feet per barrel material treated.In the step-wise application of hydrogen whereby to provide the solventsof the present invention, a few trials when using any of the startingmaterials will determine the gas flow, when coordinated with theselected temperature and pres, sure conditions to effect aforesaiddepolymerizing conditions. The gas flow in this instance may be avariable quantity because of the varying ranges of coordinatedtemperature and pressure that may be selected. When using any chosencoordination of temperature and pressure, a few trials will readilydetermine the gas ow that provides depolymerizing conditions to the endthat solvency. specic gravity, viscosity and boiling'range are lowered.

Concerning the gas flow that increases boiling intermediate startingmaterials under chosen coordination of temperature and pressure willreadily determine the desirable gas flow. For a given coordination oftemperature and pressure, the gas flow in the last instance is lower4than the gas flow in the rst instance..

Using some starting materials, a gas flow of from 10,000 to 15,000 cubicfeet per barrel, or

higher, has proven satisfactory for aforesaid depolymerizing conditions,and gas flows in the order of 46,000 to 8,000 cubic feet, or lower whenincreasing solvency and boiling range has proved satisfactory.

By the term benefciated as used herein and in the appended claims, ismeant the starting material at least once subjected to the action ofhydrogen in accordance with one or more steps of the present invention.

After the starting tar or fraction thereof has been subjected todepolymerizing action as aforestated, the stripping step may be effectedat any point selected within a wide range to provide a cut which afterfurther processing is capable of providing substitutes for benzol and/ortoluol and/or Xylol and/or naphthas, and plasticizers.

Thus the depolymerized starting material may be cut to secure a lowboiling product according to the need at hand, said low boiling cut thenbeing subjected to the action of hydrogen that increases solvency andboiling range. The residue from said cut being recycled, if desired, tothe end that substantially total conversion be eiected.

All catalysts effective in the presence of hydrogen for aforementionedpurposes are usable.v

As for instance, chromiummolybdenum, vanadium, uranium, cobalt, copperand their compounds, for instance suliides and/or oxides; promoted ornot; with Vor without small amounts of alkali, acid or halide, orderivatives thereof; small amounts of halogen or halogens, assuch, orincorporated with lother substances; effective catalysts deposited oncarriers, as for instance gels, earths, carbon, or the like; in variousshapes, as for instance forms, extruded shapes or lengths, pellets,comminuted; mixed with other material possessing desired action or not;with or without'other material effecting splitting or not.

When using catalysts, it may be desirable at times to use a comminutedcatalyst during the period of the process characterized bydepolymerization; thereafter, and during the period characterized byincrease in solvency and boiling points, to use a rigid catalyst.

By the terms multiplicity of rings, high molecular complexes andpolymerized products are meant high boiling fractions of aromaticcontent, a portion of which at least may be viewed as ring multiples;or, said terms, any or all, may be used to describe high boilingfractions of the starting material, which because of high. carboncontent are especially susceptible to thermal degradation Whensubjecting high boiling fractions of aforenamed materials to the processof the present invention, it may be desirable prior to thedepolymerizing step to at least partially depolymerize the molecularcomplexes by the use of a solvent. Said solvent may be added in smallamounts, or up to volume for volume, or more, may be used. Refractorysolvents are desirable, but others more susceptible to the reactionsinherent in and to the present process are usable.

range and solvency, a few trials with any of the COIlCelIlIlg Solvents.it may be Said that '6313 as for instance high temperature coke oven taris constituted of high molecular complexes dissolved, cut back ordepolymerized with a solvent, said solvent being the lower boilingfractions of said tar.

The depolymerizing action of hydrogen, as aforestated, may be effectedin one or more cycles or chambers, with or without releasing thepressure and with or without variations of process controls, includingchanges in either temperature, pressure and/or gas flow; the finalaction of hydrogen according to the present invention may be effected inone or more cycles or chambers, with or without releasing pressure andwith or Without variation of process controls, including changes ineither temperature, pressure and/or gas flow.

Various modes of practicing the present invention are possible; forinstance the depolymerized starting material may be stripped as forinstance by gas movement; the low ends thus stripped may then, with orwithout releasing pressure, be subjected to the action of hydrogen thatincreases solvency and boiling point. Or the desired stripped materialmay be obtained by partial release of pressure which would correspond tothe fractional recovery desired or predetermined.

The process may be practiced in a single high pressure chamber, a seriesthereof, a parallelism thereof, including a multiplicity thereof.

The solvent of the present invention may, as aforestated, befractionated to provide solvents of various boiling ranges, and in theinstance where said solvents are processed from a deep cut on thedepolymerized material, the highest boiling fractions thereof serve asespecially eicacious products in the coating industry or the like,however, no further mention is herein made of same.

The term coal tar as used herein means tar produced by the hightemperature carbonization of coal, as for instance, high temperaturecoke oven tar and gas house tar.

Minor changes may be made without departing from the spirit of thepresent invention.

I claim:

1. In the production of solvents from a mixture of high temperature coaltar fractions, the process which comprises: subjecting said mixture oftar fractions to a first action of flowing hydrogen whilst contacting acobalt compound as catalytic material, with time, temperature andpressure so controlled as to provide a beneciated material of loweredboiling range; stripping low boiling fractions from the beneciatedmaterial and subjecting at least a portion of said low boiling fractionsto a second action of hydrogen wherein the flow is less than about 8,000cubic feet per barrel material treated, with time, temperature andpressure so controlled as to increase boiling range and solvency.

2. The process of claim 1 in which the rst gas flow is in excess ofabout 10,000 cubic feet per barrel material treated and the second gasflow is selected between the limits of 2,000-8,000 cubic feet per barrelmaterial treated.

JACQUELIN E. HARVEY, JR.

